1. Field of the Invention
This invention relates to a device for rotating a sound or data recording medium in the shape of a disk, such as an optical sound recording disk which is known as a compact disk. More particularly, it is a motor and spindle assembly for rotating any such disk.
2. Description of the Prior Art
There has recently been a rapid development for the realization of a very small device for rotating a disk in a magnetic or optical recording apparatus, such as a floppy disk or a compact disk.
A typical device for rotating a compact disk is shown in FIG. 2. It includes a main body 21 in which a disk 20 mounted on a rack can be placed. The main body 21 has a vertically rotatable cover 22 which is lowered, as shown by an arrow, to close the main body 21 in which the disk 20 has been inserted. The cover 22 is provided therein with a disk holder 23 which is vertically rotatable with the cover 22. An electric motor 24 is provided in the main body 21 for rotating the disk 20. A spindle 25 is connected to the motor 24 and cooperates with the disk holder 23 to hold the disk 20 therebetween. The disk holder 23 is usually provided with a magnet which ensures that the disk 20 be held in position.
Reference is now made to FIG. 3 showing how the spindle 25 is connected to the motor 24 in a known disk rotating device. The motor 24 has an output shaft 26 about which the spindle 25 is fitted. A centering member 27 is also fitted about the output shaft 26 of the motor 24 for centering the disk with respect to the axis of rotation of the motor 24. The spindle 25 is press fitted about the shaft 26 and secured thereto. The shaft 26 has a groove 26a in which a washer 28 is engaged to hold the centering member 27 in position on the shaft 26. The washer 28 is usually an E-washer which is generally E-shaped in top plan. A spring 29 is disposed between the spindle 25 and the centering member 27 for urging the centering member 27 against the washer 28.
The known device has, however, the following drawbacks:
(1) When the spindle is press fitted about the output shaft of the motor, a large amount of stress is axially produced on the motor. It is very likely to damage the motor or its output shaft.
(2) A considerably large force is required for press fitting the spindle. It is likely to damage the device as a whole if the spindle is fitted after the motor has been installed in position. Therefore, it is necessary to connect the spindle to the motor before installing the motor in position. The spindle is, however, an obstacle when the motor is joined by screws to a frame 35 which is located between the motor and the spindle, as is obvious from FIG. 3. Therefore, it is essential to employ an additional mounting plate 30 to which the motor is joined before it is installed in position.
(3) The cutting of the groove on the output shaft of the motor for receiving the washer complicates the process for manufacturing the device.